This invention relates to die-casting machines and, more particularly to a die holder assembly having an upper mould holder with a clamp ring and a body segment.
As is well known, die-castings are produced by forcing a molten metal under pressure into one or more die cavities that are machined into a die set or into cavities that are machined, die-cut or otherwise formed in a part. For example, one exemplary part is a rotor for an electric machine. The rotor typically includes a stack of laminations that are die cut from a lamination material. The rotor laminations include rotor bar bores into which aluminum is die cast. Oftentimes, end rings are die cast on opposite ends of the stack of laminations.
A die-casting machine typically includes an upper mould and a lower mould. The die-casting machine also includes an injection system for delivering molten material, such as aluminum into the die cavity and an ejector system for ejecting the casting from the die cavity. As is conventional in horizontal die-casting machines, the lower mould is secured to the stationary cover platen while the upper mould is secured to the moveable ejector platen. The shot of molten metal is typically injected into the cavity in the part through the lower mould. Ejector pins that are associated with the ejector system extend through access holes that are formed in the upper mould. The ejector platen is mounted to a power-operated ram that is actuated to open and close the upper and lower moulds.
In order to reduce the time that is required for die changes, it is known to preassemble the die set into a die holder assembly that includes upper and lower mould holders. The upper mould holder is mounted to the ram and the lower mould holder is mounted to the stationary cover platen. To permit utilization of the die holder assembly with most die-casting machines, the upper and lower mould holders include access bores to accommodate such things as leader pins, ejector pins, and clamps for mounting the die set thereto.
An exemplary die-casting machine according to the prior art is illustrated in FIG. 1A and is generally designated 10. The die-casting machine 10 includes a frame 12 with a pair of left-side tie bars 14 and a pair of right-side tie bars 16. Upper and lower platens 20 and 22 extend between the tie bars 14 and 16. An upper ram 26 is connected to an upper ram adapter 28 that defines a mounting chamber 30 in a downwardly-facing direction. Horizontal clamp cylinders 32 and 36 extend inwardly into the mounting chamber 30. The horizontal clamp cylinders 32 and 36 reciprocally move clamp wedges 38 and 40 inwardly and outwardly in a horizontal direction. The clamp wedges 38 and 40 in conjunction with the clamp cylinders 32 and 36 releasably engage an upper mould holder 50.
The upper mould holder 50 defines an annular recess 54 on an outer surface thereof that engages the clamp wedges 38 and 40. A bottom portion 56 of the upper mould holder 50 is removably attached to upper moulds 60 and 62 that include downwardly-facing pilot projections 64. A lower mould holder 74 includes sleeves 76 and 78 for receiving the leader pins 70 and 66, respectively. A top portion 80 of the lower mould holder 74 is removably attached to lower moulds 82 and 84. The lower moulds 82 and 84 include upwardly-facing pilot projections 86. A shot ram 88 is connected to the lower mould holder 74.
Referring now to FIGS. 1A, 1B, and 1C, the projections 64 of the upper moulds 60 and 62 and the projections 86 of the lower moulds 82 and 84 are received by a rotor shaft bore 90 that is formed by a stack of interconnected rotor laminations 91. The rotor laminations 91 typically have a circular cross-section and include rotor bar bores 92 that are located adjacent a radially outer surface 93 thereof. The rotor bar bores 92 of the adjacent laminations 91 are offset or skewed at a skew angle 94 that is typically between 2 to 10 degrees. In other words, a first rotor is rotated at the skew angle relative to the adjacent rotor laminations 91. The rotor laminations 91 also include interconnects 95 that are typically formed by making die cuts that are deformed using a punch. The deformed punched portion of the die cuts in one lamination 91 is received by the die cut of an adjacent lamination 91. The interconnects 95 hold the rotor laminations 91 together during assembly. The upper and lower moulds 60, 62, 82, and 84 typically define end ring cavities (not shown) that are located adjacent opposite ends of the stack of rotor laminations 91. The molten aluminum enters the end ring cavities to create end rings 96.
When the injector pins inject molten metal such as aluminum into the rotor bar bores 92-1, the molten metal moves under pressure into one of the end ring cavities. Then, the molten metal moves under pressure back through the rotor bar bores 92-2 and into the other end ring cavity 96-2.
When the upper mould holder 50 is to be changed and/or worked on, the upper mould holder 50 is typically lowered onto the lower mould holder 74 or any other suitable support. The clamp cylinders 32 and 36 are fully retracted to move the clamp wedges 38 and 40 out of the annular recess 54. The upper ram 26 is moved upwardly to allow access to the upper mould holder 50. In other words, the upper mould holder 50 is released from the upper ram 26 and the upper ram adapter 28. Work is completed on the upper mould holder 50 or a different upper mould holder 50 is installed. The process is reversed to reattach the upper mould holder 50.
Oftentimes when the technicians attempt to reattach the upper mould holder 50 to the upper ram adapter 28, the technicians fail to retract the clamp cylinders 32 and 36. This is due, in part, to the visually obstructed position of the clamp wedges 38 and 40 that are located in the mounting chamber 30 of the upper ram adapter 28. When the technicians lower the upper ram 26 and the upper ram adapter 28 over the upper mould holder 50, the clamp wedges 38 and 40 damage a radially outer edge 92 of an upper surface 94 of the upper mould holder 50. The damage to the upper mould holder 50 can, in some cases, be repaired. The repairs, however, can be expensive. Even if the upper mould holder 50 can be repaired, subsequent accidents permanently damage the upper mould holder 50 requiring replacement.
A die-casting assembly according to the invention includes a ram and a ram adapter that is connected to the ram. The die-casting assembly further includes a mould holder and a mould that is connected to the mould holder. An attachment device includes a clamp cylinder having an end that removably connects the mould holder to the ram adapter. The mould holder includes a clamp ring that defines a radially projecting engagement flange. The upper mould holder includes a body segment having an upper surface that is removably connected to the clamp ring in a plurality of angular positions. When the clamp ring is damaged during use, the clamp ring can be rotated a plurality of times relative to the body segment without requiring repair or replacement of the upper mould holder.
In other features of the invention, the clamp ring is annular and includes a first plurality of axial bores that provide access to leader pins that are connected to the body segment. The access bores allow the leader pins to be adjusted, removed or replaced without removing the clamp ring. The clamp ring includes a second plurality of bores arranged in a first pattern for receiving bolts that connect the clamp ring to the body segment. The body segment includes a third plurality of bores arranged in a second pattern for receiving the bolts that connect the clamp ring to the body segment. The first and second patterns are positioned and arranged to allow the clamp ring to be rotated in a plurality of angular positions. Thus, the clamp ring can be rotated several times relative to the body segment when damage occurs without requiring repair or replacement of the clamp ring.
In other features of the invention, an improved mould holder includes a clamp ring with an engagement flange that projects radially from an inner surface. A first plurality of bores in the inner surface are arranged in a first pattern. The body segment defines a shoulder and a second plurality of bores arranged in a second pattern. The first and second patterns align in a plurality of angular positions. The engagement flange of the clamp ring and the shoulder of the body segment define a recess for receiving and engaging one end of a clamp cylinder.
In still other features of the invention, the clamp ring includes four axial leader pin bores in the inner surface that are spaced 90 degrees apart. The first plurality of fastening bores are located between the axial leader pin bores and are spaced 30 degrees apart. The body segment includes two axial access bores that are spaced 180 degrees apart and a first and second pair of fastening bores that are located on opposite sides of the axial access bores and are spaced at 30 degree intervals. The clamp ring and the body segment allow the clamp ring to be rotated 90 degrees and refastened when damage occurs. The leader pins that are connected to the body segment can be accessed without removing the clamp ring.
In other features of the invention, the fastening bores on the clamp ring are spaced at 60 degree intervals. The body segment includes two axial access bores that are spaced 180 degrees apart. The fastening bores on the body segment are spaced at 60 degree intervals. The clamp ring and the body segment allow the clamp ring to be rotated 60 degrees and refastened when damage occurs.
Still other objects, features and advantages will be readily apparent from the specification, the drawings and the claims.